There have been plenty of articles referring to increased cost of next gen development, so I'm not sure we'll see much drop in RRP.
However, what may be interesting is if MS go with the 'single-use' code activated release (hence no second-hand) and Sony stick to the current model. How would that difference reflect on the relative RRPs across platforms?
Since no physical packaging/shipping etc. is required for download titles then you would expect lower RRP but clearly that hasn't happened. So, if MS are in effect saying to publishers 'you will be guaranteed to get your cut from anyone who wants to play your game on our platform', I wonder if there will be a reaction from the publisher? A lower RRP on MS platform coming from [possibly] increased revenues or perhaps more/exclusive DLC as an incentive to the buyer who will not be able to go the second hand route?

I've not bought second for a number of years now, but I'd say I'm buying roughly the same number of games - maybe MS has a reasonable point but it is quite a gamble.